1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and a board for mounting the same.
2. Description of the Related Art
A multilayer ceramic capacitor, a multilayer chip electronic component, is a capacitor having a chip form mounted on a printed circuit board of an imaging device such as a liquid crystal display (LCD), a plasma display panel (PDP), and the like and various electronic products such as a computer, a smart phone, a mobile phone, and the like to thereby serve to charge or discharge electricity.
The above-mentioned multilayer ceramic capacitor (MLCC) may be used as a component of various electronic devices due to advantages such as a small size, high capacitance, easiness of mounting, or the like.
The multilayer ceramic capacitor may have a structure in which a plurality of dielectric layers and internal electrodes having different polarities from each other, having the dielectric layer interposed therebetween, are alternately stacked.
Particularly, a power supplying apparatus for a central processing unit (CPU) of a computer or the like may generate voltage noise due to a rapid change in a load current while a low level of voltage is supplied thereto.
Therefore, the multilayer capacitor has been widely used in the power supplying apparatus as a decoupling capacitor for the purpose of suppressing the voltage noise as described above.
The decoupling multilayer ceramic capacitor is required to have a lower equivalent series inductance (ESL) value as an operating frequency is increased. Therefore, research into decreasing the above mentioned ESL has been actively conducted.
In addition, in order to stably supply power, the decoupling multilayer ceramic capacitor is required to have adjustable equivalent series resistor (ESR) characteristics.
When the equivalent series resistor (ESR) value of the multilayer ceramic capacitor is lower than a required level, an impedance peak in a parallel resonance frequency caused by the ESL of the capacitor and plane capacitance of a microprocessor package may be increased and impedance in a serial resonance frequency of the capacitor may be excessively decreased.
Therefore, in order to enable a user to implement flat impedance characteristics of a power distribution network, the ESR characteristics of the decoupling multilayer ceramic capacitor need to be easily adjusted and provided.
In relation to the ESR adjustment, a method using a material having high electrical resistance for an external electrode and an internal electrode may be considered. The method using change in materials as described above may provide high ESR characteristics while maintaining a typical low ESL structure.
However, when a highly resistive material is used in the external electrode, a localized heat spot caused by a current concentration phenomenon due to a pin hole may occur. In addition, when the highly resistive material is used in the internal electrode, the material of the internal electrode should also be continuously changed for matching a ceramic material according to high capacitance.
Therefore, because the ESR adjustment method according to the related art has the disadvantages as described above, research into the multilayer ceramic capacitor capable of adjusting the ESR remains required.
In addition, a microprocessor has also been switched to a miniaturized, highly-integrated product, in accordance with the recent trend for rapid development of mobile terminals such as tablet PCs, ultrabooks, and the like.
Thereby, an area of the printed circuit board is decreased and a space for mounting the decoupling capacitor is also similarly limited. As a result, the multilayer ceramic capacitor capable of satisfying the decreased and the limited space has been continuously required.